- `http_404_request_duration_ms` (the amount of time the server took to respond in ms)

  Also includes percentile groupings. The directory for the default 404 handler includes instructions on how to enable prometheus for monitoring and setting alerts.
  ([#79106](https://github.com/kubernetes/kubernetes/pull/79106), [@vbannai](https://github.com/vbannai))

### Instrumentation

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community
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community-pro.net
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condos
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conf.se
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- Using exec auth plugins with kubectl no longer results in warnings about constructing many client instances from the same exec auth config. ([#97857](https://github.com/kubernetes/kubernetes/pull/97857), [@liggitt](https://github.com/liggitt)) [SIG API Machinery and Auth]

- The `client.authentication.k8s.io/v1alpha1` ExecCredential has been removed. If you are using a client-go credential plugin that relies on the v1alpha1 API please contact the distributor of your plugin for instructions on how to migrate to the v1 API. ([#108616](https://github.com/kubernetes/kubernetes/pull/108616), [@margocrawf](https://github.com/margocrawf))

### Documentation

- Updated the instructions for deploying the sample app. ([#82785](https://github.com/kubernetes/kubernetes/pull/82785), [@ashish-billore](https://github.com/ashish-billore)) [SIG API Machinery]

### Failing Test

* Marked scheduler's scheduling_duration_seconds Summary metric as deprecated ([#86586](https://github.com/kubernetes/kubernetes/pull/86586), [@xiaoanyunfei](https://github.com/xiaoanyunfei))
* Add instructions about how to bring up e2e test cluster ([#85836](https://github.com/kubernetes/kubernetes/pull/85836), [@YangLu1031](https://github.com/YangLu1031))

    * Fix detect exceptions plugin to analyze message field instead of log field.
    * Fix detect exceptions plugin to analyze streams based on local resource id.
    * Disable the metadata agent for monitored resource construction in logging.
    * Disable timestamp adjustment in logs to optimize performance.
    * Reduce logging agent buffer chunk limit to 512k to optimize performance.

    * Fix detect exceptions plugin to analyze message field instead of log field.
    * Fix detect exceptions plugin to analyze streams based on local resource id.
    * Disable the metadata agent for monitored resource construction in logging.
    * Disable timestamp adjustment in logs to optimize performance.
    * Reduce logging agent buffer chunk limit to 512k to optimize performance.

    * Fix detect exceptions plugin to analyze message field instead of log field.
    * Fix detect exceptions plugin to analyze streams based on local resource id.
    * Disable the metadata agent for monitored resource construction in logging.
    * Disable timestamp adjustment in logs to optimize performance.
    * Reduce logging agent buffer chunk limit to 512k to optimize performance.

- Kubeadm: fixes a preflight check that can fail hostname construction in IPV6 setups ([#134590](https://github.com/kubernetes/kubernetes/pull/134590), [@liggitt](https://github.com/liggitt)) [SIG API Machinery, Auth, Cloud Provider, Cluster Lifecycle and Testing]